Nonwoven preform technology enables the production of high performance carbon brakes for both aerospace and automotive applications. This technology typically involves needle-punching oxidized polyacrylonitrile (“PAN”) nonwoven fabric segments into an annular ring (a “preform”) using an annular needling machine. However, the present invention is not necessarily limited to annular needlers. Similar beneficial results can be obtained with other needlers common in the industry for producing carbon preforms.
Competition drives lower cost in the market place for aircraft friction materials. At the same time, the market demands improvements to on-time delivery and superior product performance. In order to help achieve these goals, improvements to the manufacturing processes of C—C composites used as friction materials are constantly being made.
The following patents provide background on the production of carbon-carbon composite friction materials
EP 1 724 245 A1 (Simpson et al.) describes a process for producing carbon-carbon composite preform, by: providing short carbon fiber or fiber precursor segments; providing particulate pitch; combining the fiber segments and pitch particles in a mold; subjecting the resulting mixture to elevated pressure to create an uncarbonized preform; placing the preform in a constraint fixture; and carbonizing the combined components in the constraint fixture at an elevated temperature to provide a preform having a desired density.
EP 0 946 455 B1 (Murdie et al.) discloses a carbon-carbon composite material made by providing an open-celled carbon foam preform and densifying the preform with carbonaceous material. The carbon-carbon composite material can be heat treated to provide thermal management materials, structural materials, or friction materials for use in brake or clutch mechanisms.
WO 2006/101799 A2 (Fryska et al.) describes an invention in which small ceramic particles (e.g., of TiC) are incorporated into fibers. The ceramic particles enhance the friction and/or wear properties of a carbon-carbon composite article made with the impregnated or coated fibers.
US 2008/0090064 A1 (James et al.) discloses a carbon-carbon composite material comprising carbonized woven or nonwoven fabric-based preforms. A method taught in this document contemplates densifying the preform and subsequently adding a ceramic additive thereto in order to enhance the properties of the final product.
US 2008/0041674 A1 (Walker et al.) discloses annular drive inserts which are placed within an annular opening within a brake disk. The annular drive inserts may comprise carbon-carbon composite which has been treated with antioxidant.
U.S. Pat. No. 7,374,709 B2 (Bauer) describes a method in which specific end-use application friction requirements are satisfied by tailoring a level of carbon in a selected carbon/carbon preform, heat treating the carbon/carbon composite preform to affect thermal conductivity so as to optimize overall braking performance prior to ceramic processing, and by selecting an optimum level of ceramic hard phase to achieve satisfactory friction disc wear life and friction characteristics of a resulting braking material.